plyr/src/sass/states/fullscreen.scss

// --------------------------------------------------------------
// Fullscreen
// --------------------------------------------------------------

.plyr:fullscreen {
    @include plyr-fullscreen-active();
}

.plyr:-webkit-full-screen {
    @include plyr-fullscreen-active();
}

.plyr:-moz-full-screen {
    @include plyr-fullscreen-active();
}

.plyr:-ms-fullscreen {
    @include plyr-fullscreen-active();
}

// Fallback for unsupported browsers
.plyr--fullscreen-fallback {
    @include plyr-fullscreen-active();

    position: fixed;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    z-index: 10000000;
}